CHEMICAL ROUTES TO MATERIALS 3D structures of hydroxyapatite obtained from Rapana venosa shells using hydrothermal synthesis followed by 3D printing Ana Maria Mocioiu 1 , Raluca Tutuianu 2 , Laura Madalina Cursaru 1, * , Roxana Mioara Piticescu 1 , Paul Stanciu 1 , Bogdan Stefan Vasile 3 , Roxana Trusca 3 , Viviana Sereanu 4 , and Aurelia Meghea 4 1 National R&D Institute for Non-Ferrous and Rare Metals, INCDMNR-IMNR, 102 Biruintei Blvd., 077145 Pantelimon, Ilfov, Romania 2 Institute of Cellular Biology and Pathology ‘Nicolae Simionescu’, 8 B.P. Hasdeu Street, District 5, 050568 Bucharest, Romania 3 National Research Center for Micro and Nanomaterials, University Politehnica of Bucharest, No. 313 Splaiul Independentei Street, Bucharest, Romania 4 Faculty of Applied Chemistry and Materials Science, University POLITEHNICA of Bucharest, 1-7 Polizu, District 1, Bucharest, Romania Received: 5 April 2019 Accepted: 22 July 2019 Published online: 31 July 2019 Ó Springer Science+Business Media, LLC, part of Springer Nature 2019 ABSTRACT In this study, hydroxyapatite (HAp) obtained by hydrothermal synthesis from natural sources (whelk shells of Rapana thomasiana) was compared to synthetic hydroxyapatite (prepared from chemical reagents) and used for 3D printing of HAp-based structures. Rapana thomasiana can be found in Romanian coast of Black Sea. The visceral part of Rapana is used for culinary purposes, but the whelk shell, mainly consisting of CaCO 3 , remains as biowaste and can be used as a source of Ca for hydroxyapatite synthesis. Synthetic and natural hydrox- yapatite nanopowders were characterized by X-ray diffraction (XRD), Fourier- transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), dynamic light scattering (DLS) method and in vitro tests. XRD and FT-IR have confirmed the formation of nanostructured hydroxyapatite irrespective of the raw material used. Both types of powders were further used for 3D printing of HAp-based structures, which have also been characterized by SEM and in vitro tests. In vitro tests performed on natural HAp disks (made from whelk shell) lack cytotoxicity and were associated with cell viability similar to that for the synthetic hydroxyapatite disk. Address correspondence to E-mail: mpopescu@imnr.ro https://doi.org/10.1007/s10853-019-03872-3 J Mater Sci (2019) 54:13901–13913 Chemical routes to materials